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CHAPTER 6
A Tour of the Cell
You Must Know
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3 diff. prokaryotic and eukaryotic cells.
Common organelles (Plant/Animal)
Unique organelles (Plant/Animal)
Organelles > Cell Function
Size and Shape affect rate of nutrient/waste
Tuesday
December 1st
Agenda:
Checklist for Chapter 6
Due Thursday
Videos:
1. Introduction to Cells
Wednesday
December 2, 2015
Agenda:
1. Surface area to volume
demonstration
2. Checklist for Chapter 6
Due Tmrw
Videos:
1. Cell Size
What factors constrain cell size?
Surface Area to Volume Ratios
• Need a large surface area to accommodate for
growing demands of cell – energy, nutrients,
wastes, gasses
• More cells vs. Larger cells
• Cells must be small to maintain a large surface area to
volume ratio
• Large S.A. allows  rates of chemical exchange
between cell and environment
Practice Problem
Simple cuboidal epithethial cells line the ducts
of certain human exocrine glands. Various
materials are transported into and out of the
cell by diffusion. What would be the volume
of the larger cell in um3?
SA Formula: 6 x S2
Volume: S3
S = length of side
10 um
20 um
Surface Area Example (Animal):
Small Intestine: highly folded surface to increase
absorption of nutrients
– Villi: finger-like projections on SI wall
– Microvilli: projections on each cell
Diverticulitis of the colon
Surface Area Example (Plant):
Root hairs: extensions of root epidermal cells;
increase surface area for absorbing water and
minerals
Thursday – December 3rd
Agenda:
Ch 6 Check for Understanding
Microscope Lab
Chapter 6
Check for Understanding
1. What are the 2 main types of cells? Which Domains
do they consist of?
2. List 3 ways that eukaryotes differ from prokaryotes.
Special Note: Archaea and
bacteria generally lack internal
membranes and organelles and
have a cell wall.
2 Types of Cells:
1. Prokaryotes: Domain Bacteria & Archaea
2. Eukaryotes (Domain Eukarya): Protists, Fungi,
Plants, Animals
A Prokaryotic Cell (bacteria)
Commonalities
Prokaryote and Eukaryote
• Plasma Membrane
• Ribosomes (Not membrane bound in P)
• DNA:
– Prokaryote: Region, Circular Chromosome
– Eukaryote: Nucleus, Linear Chromosome
Summary
Prokaryote Vs. Eukaryote
• “before” “kernel”
• No nucleus, DNA in a
nucleoid
• Cytosol
• No organelles other than
ribosomes
• Small size
• Primitive
• i.e. Bacteria & Archaea
• 1-10 um
• “true” “kernel”
• Has nucleus and nuclear
envelope
• Cytosol
• Membrane-bound
organelles with specialized
structure/function
• Much larger in size
• More complex
• i.e. plant/animal cell
• 1-100 um
Chapter 6
Check for Understanding
Compare and contrast Animal vs. Plant Cells
Animal Cell
Plant Cell
Parts of plant & animal cell p 108-109
Endosymbiont theory
• Mitochondria &
chloroplasts share similar
origin
• These prokaryotic cells
engulfed by ancestral
eukaryotic cells
• Evidence:
– Double-membrane structure
– Have own ribosomes & DNA
– Reproduce independently
within cell
For the AP Exam
Know the function of the cytoskeleton.
Not needed. Specifics on structure & function of:
1. Microtubules
2. Microfilaments
3. Intermediate filaments
For the AP Exam
NOT NEEDED FOR THE EXAM….
1. Plasmodesmata
2. Gap junctions
3. Tight junctions
4. Desmosomes
Friday December 4th
Agenda:
Organelles Review
Chapter 7 Checklist
–
Due Monday
Warmup Worksheet
Chapter 6
Part 1
Organelles
What is the function of an organelle?
Why does the cell compartmentalize?
What are some commonalities
between the nucleus,
mitochondria and chloroplast?
Structure
Function
Mitochondria
• Function: site of cellular respiration
• Double membrane: outer and inner
membrane
• Cristae: folds of inner membrane; contains
enzymes for ATP production; increased surface
area to  ATP made
• Matrix: fluid-filled inner compartment
Chloroplasts
• Function: site of photosynthesis
• Double membrane
• Thylakoid disks in stacks (grana); stroma
(fluid)
• Contains chlorophylls (pigments) for
capturing sunlight energy
Other types of plastids
• Amyloplastids: colorless plastids that store
starch in roots and tubers
• Chromoplasts: Store colored pigments for
fruits and flowers
Tubers are various types of modified
plant structures that are enlarged to
store nutrients. Used to survive the
winter or dry months, to provide
energy and nutrients, and a means of
asexual reproduction.
What is the relationship between
the nucleus and the
endomembrane system?
Nucleus
• Function: control center of cell
• Contains DNA (code for making proteins)
• Surrounded by double membrane (nuclear envelope)
– Continuous with the rough ER
– Supported by protein filament network called nuclear lamina
• Nuclear pores: control what enters/leaves nucleus
Inside of the nucleus –
• Nuclear matrix – internal support , protein framework
• Chromatin: complex of DNA + proteins; makes up
chromosomes
• Nucleolus: region where ribosomal subunits are formed
• Prokaryote: Nucleoid Region- dense region
Nucleus
• Contains DNA
• Function: control center of cell
• Surrounded by double membrane (nuclear envelope)
– Continuous with the rough ER
• Nuclear pores: control what enters/leaves nucleus
• Chromatin: complex of DNA + proteins; makes up
chromosomes
• Nucleolus: region where ribosomal subunits are
formed
DNA to
Chromatin to
Chromosome
Do all eukaryotic cells have a
single nucleus?
Ribosomes
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Function: protein synthesis
Composed of rRNA + protein
Large subunit + small subunit
Types:
1.
2.
Free ribosomes: float in cytosol, produce proteins used within
cell
Bound ribosomes: attached to ER, make proteins for export
from cell
Nuclear Envelope
ER
Golgi
Lysosomes
Vesicles
Vacuoles
Plasma Membrane
ENDOMEMBRANE SYSTEM:
Regulates protein traffic & performs
metabolic functions in the cell
Endoplasmic Reticulum (ER)
“Within the cytoplasm” - “Little net”
1. Rough ER: ribosomes on surface
Function: package proteins for secretion, send
transport vesicles to Golgi, make replacement
membrane
2. Smooth ER: no ribosomes on surface
Function: synthesize lipids, metabolize carbs, detox
drugs & poisons, store Ca2+
What types of lipids are synthesized
in the smooth ER? Where (in the
human body) would we find a lot of
SER for this purpose?
What type of body cells would
have a high number of Smooth
ER for detoxification?
Barbiturates – CNS Depressants
Anxiety, Seizures and Sleep Disorders
Example: Alcohol
• Induce the proliferation (growth of production) of
smooth ER and it’s detoxification enzymes
(increase the rate)
• In turn, this increases your tolerance
• Can also decrease effectiveness to drugs you
need – like antibiotics
Golgi Apparatus
Function: synthesis & packaging of materials
(small molecules) for transport (in vesicles);
produce lysosomes
Series of flattened membrane sacs (cisternae)
 Cis face: receives vesicles
 Trans face: ships vesicles
Lysosomes
• Function: intracellular digestion; recycle cell’s
materials; digestion in prokaryotes
• Contains hydrolytic enzymes
What happens if a lysosome
accidentally ruptures in the cell?
What is the name of the
lysosomal disorder where
individuals lack the enzyme
needed to breakdown lipids?
Peroxisomes
• Functions: break down fatty acids for the
mitochondria; detox alcohol
• Contain catalase, Involves production of hydrogen
peroxide (H2O2)
Vacuoles
• Function: storage of materials (food, water,
minerals, pigments, poisons)
• Eg. food vacuoles, contractile vacuoles (pump)
• Plants: large central vacuole -- stores water,
ions
Why would the construction of a
protein take place through a long
system? Why not just one
organelle?
Cilia & Flagella
Flagella: long and few; 10-200 microns, propel through water
Cilia: short and numerous; 2-20 microns, locomotion or move fluids
Let’s begin Chapter 7!